YSI DO200 Dissolved Oxygen and Temperature Meter

Overview

The YSI DO200 Dissolved Oxygen and Temperature Meter is a field-deployable, handheld instrument engineered for rapid, reliable measurement of dissolved oxygen (DO) concentration in water—expressed both as mg/L and % air saturation—and concurrent temperature. It employs a Clark-type polarographic sensor with a next-generation polyethylene (PE) membrane, delivering fast response times (<15 seconds to 90% step change) and reduced hydrodynamic dependence compared to conventional membranes. This design minimizes stirring artifacts during spot measurements in low-flow or stagnant environments—such as ponds, wetlands, effluent channels, or shallow groundwater wells—without requiring forced flow or probe agitation. The instrument’s embedded thermistor provides high-resolution temperature readout (±0.2 °C), enabling real-time automatic temperature compensation of DO values per the Winkler-derived calibration algorithms compliant with ISO 5814 and ASTM D888. Its compact form factor, ergonomic single-hand interface, and ruggedized construction support routine use across municipal wastewater treatment plants, environmental consulting field teams, academic limnology studies, and regulatory compliance monitoring programs.

Key Features

• IP65-rated housing ensures dust-tightness and protection against low-pressure water jets—suitable for rain-exposed field deployment and splash-prone sampling locations.
• Stainless steel sensor tip with integrated polymer protective sleeve resists mechanical abrasion during repeated immersion and bottom-contact sampling in rocky or sediment-laden water bodies.
• Strain-relief connector at the cable junction mitigates torsional and flexural fatigue, significantly extending service life under frequent coiling/uncoiling cycles typical in mobile survey operations.
• Selectable cable lengths (4 m standard; optional 10 m) accommodate diverse depth requirements—from surface scum layer profiling to mid-depth reservoir transects—without compromising signal integrity.
• Onboard automatic temperature compensation eliminates manual correction steps; user-adjustable salinity (0–70 ppt) and barometric pressure (500–1100 hPa) inputs ensure accuracy across estuarine gradients and altitudinal variations.
• Backlit LCD display supports legible readings under low-light conditions (e.g., pre-dawn river surveys or shaded stormwater outfalls); intuitive menu navigation requires no training documentation.

Sample Compatibility & Compliance

The YSI DO200 is validated for use in freshwater, brackish water, and wastewater matrices—including activated sludge, trickling filter effluents, and aerated lagoons—within pH 4–10 and conductivity up to 20 mS/cm. It meets functional requirements outlined in US EPA Method 360.1 for field DO determination and aligns with performance criteria specified in ISO 5814:2012 (Water quality — Determination of dissolved oxygen — Electrochemical probe method). While not certified for GLP or 21 CFR Part 11 environments due to its non-auditable data storage architecture, it serves as a primary field verification tool in QA/QC workflows supporting ISO/IEC 17025-accredited laboratories. Calibration verification is traceable to NIST-certified zero-oxygen and saturated-air standards.

Software & Data Management

The DO200 operates as a standalone meter without proprietary software dependency. All measurements are displayed in real time and retained in volatile memory only during active operation—no internal data logging or USB export capability is included. Users intending to archive results must manually record values or integrate the device into third-party field data capture systems via visual transcription. For organizations requiring electronic records, pairing with validated mobile applications (e.g., ESRI Field Maps or ODK Collect) enables structured metadata tagging—including GPS coordinates, operator ID, and sampling time—consistent with EPA Region 10 Field Sampling Guidance protocols.

Applications

• Routine DO profiling in wastewater treatment process control points (influent, aeration basins, secondary clarifiers).
• Ecological assessment of hypolimnetic oxygen depletion in stratified lakes and reservoirs.
• Regulatory compliance monitoring for NPDES discharge permits requiring dissolved oxygen minimum thresholds.
• Educational field labs demonstrating oxygen solubility relationships with temperature, salinity, and atmospheric pressure.
• Emergency response screening following chemical spills or algal bloom events where rapid DO depression indicates biological oxygen demand surges.

FAQ

Does the DO200 support automatic barometric pressure compensation?
No—barometric pressure must be entered manually prior to measurement using the keypad interface.
Can the instrument be calibrated in-situ without removing the probe from water?
Yes; the zero-point and span calibrations can be performed directly in the field using sodium sulfite solution (zero) and air-saturated water (span), following ASTM D888 Annex A1 procedures.
Is the PE membrane replaceable by the end user?
Yes—YSI supplies factory-certified replacement membranes (part #5814-00) and electrolyte solution (part #5814-01); full replacement takes <90 seconds with no tools required.
What battery type does the DO200 use, and what is its typical field life?
It uses two AA alkaline batteries, providing approximately 200 hours of continuous operation under typical ambient temperature conditions (20 °C); low-battery indication appears 15 minutes before shutdown.
Is the DO200 suitable for seawater applications?
Yes—with manual salinity input up to 70 ppt, though long-term immersion in full-strength seawater (>35 ppt) is discouraged without post-use freshwater rinse to prevent chloride-induced electrode drift.